I am remodeling/finishing my attic in my 1922 home. Currently, the A/C air handler is in a room in the attic and the duct work that serves the rest of the house is on the floor along the outside perimeter, which means my supply registers for the attic that are punched into the ducts and my return are at floor level. I'm having trouble cooling this room and have read through the other messages on cooling suggestions for a third floor (closing off downstairs registers, zoning the system - too expensive!, etc.). I have already added insulation with proper ventilation to the roof.

My question - would it make a significant difference to raise the supply and/or return to the top of my ceiling? I have a "hip" roof with knee walls on each side, so the ceiling is about 11 feet high in the middle of the room and slopes down to 4' at the knee walls. I would have to box in the ductwork along the ceiling and it wouldn't be that attractive, so I don't want to do it if it won't help much. If I do, which would give more bang for the buck - raising the supply or raising the return? I could more easily raise the supply using smaller flexible duct than a larger metal return, but if I leave the return as is it will be on the floor of a large walk-in closet. Any thoughts?

Thanks,
Ben